They mention in the movie that their ability to use the force is diminished. Yoda being particularly strong was able to sense what was going on, the others who were not as powerful were also distracted by being personally engaged in battle and likely had to focus all of their force abilities on the here and now to help protect themselves and their troops (although that did not work out hat well for them in the end).

They just showed Jedi that were intensely engaged in combat or at least actively focused on their known foes, so that explains it a bit. Maybe the unengaged Jedi in the Temple would have been more able to detect the intent of the force marching their way.

Also could be due to a certain degree of blindness towards the troopers due to their clone nature. I think that the nature of their cloning and mental programming might affect their brains in such a way to make them more automatons than emotional actors of their own free will, thus masking what in most people could be felt as personal desire or consideration.